Brake mechanism for lifting jacks



Oct. 9, 1928. 1,687,127

F. L. GORMLEY BRAKE MECHANISM FOR LIFTING JACKS Inventor: FranhLGormley,

Patented Get. 9, 1928 UNITED STATES PATENT-OFFICE.

FRANK L. GORMLEY, OF BROOKLINE, MASSACHUSETTS, ASSIGNOR TO THE BUDA COM- PANY, OF HARVEY; ILLINOIS, A CORPORATION.

BRAKE MEGHANISIE FOR LlFTING- JACKS.

Application filed December 21, 1926. Serial No. 156,110.

This invention relates to brake mechanisms for machines and is particularly well adapted for use in connection with self-lowering lifting jacks. I

The object of the invention is to provide a means whereby the speed of lowering under a heavy load 'may be controlled by the operator and whereby under a light load the'lowering may be accomplished with greater rapidity, means being associated with the con trolling mechanism for positively locking such mechanism and preventing its operation when a load is to be retained for sometime in its elevated position.

This object is attained by the mechanism illustratedin the accompanying drawings.

For the purpose of illustrating the invention, one preferred form thereof is illustrated in the drawings, this form having been found to give satisfactory and reliable results, although it is to be understood that the various instrumentalities of which the invention consists can be variously arranged and organized, and the invention is not limited to'the precise arrangement and organization of these instrumentalities as herein shown and described except'as required by the scope of the appended claims.

Of the drawings:

Figure 1 represents a. plan of a brake mechanism embodying'the principles of the present invention, a portion thereof being shown in section.

Figure 2 represents a vertical section of same on line 2,2, on Fig. 1. I

Figure 3 represents a vertical section of same on line 3, 3, on Fig. 1. I

Figure 4 represents an elevation of a portion of the shoe carrying disk and showing one of the shoes carried thereby.

Figure 5 represents a vertical section'of a portion ofa lifting jack showing the means for revolving the speed reduction gearing in one direction only.

Figure 6represents a section ofthe one way clutch mechanism on line 6, 6, onFig. 5.

Similar characters indicate like parts throughout the several figures of the draw- IDOS.

Tn the drawings 10 is a portion of the easing of a lifting jack to which is secured the member 11 by means of bolts 12.

This member 11 has a chamber 13 therein and at the top thereof is a depression 14 cov- .of'the present invention.

ered by aplate 15- secur'edto the member 11 by screws 16.

Between the chamber 13 and depression 14 is the partition 17 through which extends the upper end of a shaft 18 having a worm 19 formed thereon, the lower reduced end 20 of said shaft being mounted in an antifriction bearing 21 in the bottom of the'member 11.

The worm 19 meshes with the worm gear 22 keyed to a flanged member 23 loosely mounted upon a pawl carrying member 24 keyed to a horizontal shaft 25 having a worm 25 thereon meshing with a worm gear'251 on the driving shaft 2520f a lifting jack.

The pitchof the" thread of the worm 25 on the horizontal shaft 25 is such as to permit it to be rotated by the gear 252 in whichever direction the driving shaft 251 is rotated.

The pawl 24 mounted on a pin 241 carried by the pawl carrying member 24 rides over the ratchet teeth 23 on the flanged member 23 when the member 24 is moving in one direction 'and engages with these teeth 23 when the member 24 is rotating in'the opposite direction. Due to this mechanism the worm gear 22 and worm 19 can rotate unnecessary to show and describe the same in the present application, to any greater extent than is illustrated in Fig. 5 as the particular means employed to impart rotary motion to said worm gear forming no part While the shaft 25 may be *revolvedin either direction the worm 19'is revoluble in one direction only and that is in the direction which permits the lowering of the load. Some means is required to control the speed of rotation of this worm 19 in order to regulate the lowering of the ram of the lifting jack of which the brake mechanism forms apart. i

This controlling means consists of a disk 26 having a peripheral groove27 therein in which are disposed aplurality of shoes 28 each pivoted at one end to the disk 26 byapin29.

As the disk rotates in the direction of the arrow a on Fig. 1 the free ends of the shoes 28 will be moved outwardly by centrifugal force.

Pivoted at 30 to the partition 17 are two brake arms 31 which are curved to fit around the periphery of the disk 26 and have at their free ends substantially parallel portions 32, between which is disposed a cam member 33 secured to or formed integral with a pin 34: extending upwardly through the top plate or cover 15, the upper end of said pin having an actuating leverlA secured thereto.

The lower end of the pin 34 has a bearing in the partition 17.

friction between the shoes 28 and arms 31 to prevent the rotation of the ram under the load supported thereby.

If it is desired to lower the load the operator moves the lever 34* in the direction of the arrow 64 on Fig. 1, thereby separating the arms 31 to a greater extent and reducing the friction between the contacting faces of the shoes 28 and arms 31.

By properly manipulating the lever 34* any desiredamount of friction between arms 31 and the shoes 28 may be obtained and as a consequence any desired speed of lowering may be attained.

-When lowering a heavy load it is imperative that frictional contact be maintained between the shoes 28 and the arms 81.

Sometimes, however, it is desired to lower more rapidly and this is particularly true when there is a light load on the ram and in this case there is no need 'of a frictional contact between the shoes 28 and arm 81.

In such a case it is necessary to move the arms 31 about the pivot 80 a sufficient distance to break all contact with the shoes 28 and somemeans must be provided therefore to limit the outward movement of the shoes 28.

To accomplish this each shoe 28 is providednear its outer end with an elongated slot 35 through which extends a pin 36 mounted in the disk'26.

()bviously when the inner end of the slot 35 comes into contact with the pin 36* further outward movement of the shoe 28 is prevented and it cannot follow the outward movement of the arm 31.

This feature is of great importance as provision is made whereby a slow rotation of the worm 19 at any desired speed may be obtained when a heavy load is being lowered the friction of the brake mechanism which includes springs for forcing brake arms against a' rotating disk or shoes carried thereby.

7 It has been found objectionable to depend upon springs where the load is to be left elevated for a considerable period and therefore it positlve lock has been provided to coact with the worm 19 to prevent its ro-i.

tation under the weight of the load. s This lock consisits of a screw 87 radiating from the a:-;1s of the worm 19 and prov ded at its inner end with a head 88 of soft metal which may be jammed against the thread of the worm and effectually prevent its ro-l tation regardless of the weight supported.

The screw 8? is threaded to the member 11 and has on its outer end a winged turning member 39. i i I Under normal conditions the head 38 is free from contact with the worm 19.

It will be apparent, therefore, that the worm 19 has coacting therewith both a positive lock and also means whereby its rotation may be controlled to a slow speedunder a heavyload or to a greatly increasedspeed under a light load.

Preferably the slots 35 are of different lengths so that the three pawls 28 when moved outwardly by centrifugal force successively come into contact with the pins 36 which limit their outward movement.

As a consequence, as the brake arms 31- are separated the frictional contact is first removed from one pawl, then from another pawl and finally from the third pawl.

This is a great advantage as a much greater variation of frictional contact between the brake arms 31 and shoes 28 is obtained. g

It is believed that the operation and many advantages of the invention will .be understood without further description.

Having thus described my invention, I elaim i 1. The combination of a rotatable worm; a worm gear meshing therewith and rotatable in one direction only; a disk carried by the worm shaft having a peripheral groove; brake shoes pivotally mounted in the groove of said disk and adapted to be movedoutwardly about their pivots by centrifugal force during the rotation of said shaft; and adjustable brake arms with the inner faces of which the free ends of said shoes coact.

2. The combination of a rotatable worm; a worm gear meshing therewith and rot-atable in one direction only; a diskcarried by the worm shaft; brake shoes pivoted to said disk and adapted to be moved outwardly by centrifugal force during the rotation of said shaft; pins carried by said disk and extending through elongated slots in said shoes to limit the outward movement of said shoes; and adjustable brake arms with which said shoes eoact. v

3. The combination of a rotatable worm; a worm gear meshing therewith and rotatable in one direction only; adisk carried by the worm shaft; brake shoes pivoted to said disk and adapted to be moved outwardly 57y centrifugal force during the rotation of said shaft; two pivoted brake arms opposite the periphery of said disk; a cam between the free ends of said arms; springs for retaining said free ends in contact with the cam; means carried by said disk and coacting with shoulders on said shoes for limiting the outward movement of said shoes; and means for moving said cam to separate said arms.

4. The combination of a rotatable worm; a worm gear meshing therewith and rotatable in one direction only; a disk carried by the worm shaft; brake shoes pivoted to said disk and adapted to be moved outwardly by centrifugal force during the rotation of said shaft; brake arms with which said shoes coact; and means for successively lim iting the outward movement of said shoes. 5. The combination of a rotatable worm;

a worm gear meshing therewith and rotatable in one direction only; a disk carried by the worm shaft; brake shoes pivoted to,

said disk and adaptedto be moved outwardly by centrifugal force during the rotation of said shaft, said shoes having slots of varying length in their free ends; brake arms with which said shoes coact; and pins on said disk extending through said slots andadapted to successively contact with the inner ends of aid slots.

6. The combination of a rotatable worm; a-worm gear meshing therewith and rotatable in one direction only; a disk Carried by the worm shaft having a peripheral groove; brake shoes "pivotally mounted in the groove of said disk and normally bearing at their outer ends against the bottom of the groove and pro ect1ng slightly beyond the wens or said groove, sald shoes being adapted to move outwardly about their pivots by centrifugal force during the rotation of said haft; adjustable brake arms with the inner faces of which the projecting portions of said shoes normally engage; and means carried by said disk for limiting the outward movement of said shoes when said brake arms are separated.

Signed by me at 746 Old Boston ass this 27th Clay of November, 1926.

FRANK L. GORMLEY;

South Bldg, 

